In vitro permeability analysis, pharmacokinetic and brain distribution study in mice of imperatorin, isoimperatorin and cnidilin in Radix Angelicae Dahuricae.

Coumarins are important constituents of Radix Angelicae Dahuricae, a well-known traditional Chinese medicine possess several known bioactivities with potentials in the treatment of central nervous system diseases. By using an HPLC-MS/MS method, we analyzed the in vivo plasma and brain pharmacokinetics of three ingredients of coumarins, including imperatorin, isoimperatorin and cnidilin in mice after oral administration of Dahuricae extract at doses of 800mg/kg. The biosamples were prepared using acetonitrile precipitation and the separation was achieved on an XDB-C18 column by gradient elution. The BBB permeability and P-gp-mediated efflux were further examined in Madin Canine kidney cells transfected with full length cDNA for human multidrug resistance gene1 (MDCKII-MDR1). Our results demonstrate that the method has excellent and satisfactory selectivity, sensitivity, linearity, precision, and accuracy for simultaneous determination of imperatorin, isoimperatorin and cnidilin. The pharmacokinetics parameters were determined by using noncompartmental analyses, including the AUC(0-t) in plasma (1695.22, 1326.45 and 636.98mg*h/L), the AUC(0-t) in brain (1812.35, 2125.17 and 1145.83ng*h/g) as well as the T1/2 in plasma (0.66, 0.82, 0.97h) and brain (0.96, 1.1, 0.99h) for imperatorin, isoimperatorin and cnidilin, respectively, suggesting that the three coumarins could easily pass through the BBB in vivo. In the in vitro model we observed high permeability of imperatorin and isoimperatorin with the P-gp-mediated efflux ratios of 0.53 and 0.06, as well as medium permeability of cnidilin with 0.82. All data suggest that these three coumarins have high BBB permeability and have pharmacokinetic potentials for the treatment of central nervous system diseases.